In a dim room inside a prison, a disparate group gathers—some gamble, others sip coffee, and a few chat as if at a party. Curtains are drawn back to reveal bars, and the gathering centers on the upcoming execution of Nick Ross, Ralf Harolde. The man at the center, Ross, who has never confessed, insists there was no promised commutation from a benefactor and begins to recount the true events that led to the crime, hoping to win his release. But as he speaks, he suddenly collapses, the victim of a poisoned dart.
District Attorney Roger Phillips, [Ricardo Cortez], takes charge of the tense room, coordinating with his girlfriend crime reporter Geri Reynolds, [Joan Woodbury], and his eager young receptionist Tommy to untangle the mystery. He directs a methodical search for the murder weapon and has everyone return to their original seats to relive the scene. The investigation quickly focuses on the elderly Lanning, [Harry Holman], whose cigarette holder could double as a dart blower. Lanning denies guilt but is arrested, casting a shadow over the proceedings.
Geri Reynolds is sent to the prison to uncover more clues, and Roger tasks her with getting close to Lowell King, [George Pembroke], a parole board appointee. After Roger is rebuked for arresting Lanning, he asks Geri to interview Ross’s onetime girlfriend, Verne Drake, [Iris Adrian]. Verne defends Ross but concedes he made a phone call from her apartment on the day of the murder; she recalls only part of the number, and soon after Geri leaves, Verne receives a threatening phone call.
Roger assigns Collins, [Jack Mulhall], to shadow Verne and he soon connects the dots to King via the telephone number. He also notices a coded mark on the back of King’s business card and enlists Tommy to crack the clue. Verne, meanwhile, plans to leave town and tries to recover money she gave Reed, J. Reed, head of the anti-capital-punishment organization. Reed, who was at the execution, accompanies Verne to the bank, but Verne dies suddenly after honking the car horn.
Collins catches Reed as he tries to flee, and Roger discovers a poisoned dart embedded in the steering wheel—the same weapon that killed Ross. Reed is arrested, and Lanning is freed from custody.
One evening, Geri and Bates, a fellow reporter, dine at Garrick’s café, where Geri’s check is refused. King steps in to help, and a waiter takes King’s check to Garrick, who burns it and gives the waiter a bundle of money. King then passes the money to Geri, still paying her bill.
Later, while waiting for Roger at his office, Geri realizes that the code on King’s card points to a library book. Tommy arranges for the toxicology book to be checked out, while Verne’s actions throughout the night tighten the circle of clues. The library book reference is linked to Gordon, who had checked it out, and to the five $500 bills found in Geri’s purse, hidden among smaller notes, hinting at a broader payoff.
As the investigation closes in, King’s role becomes clearer. A late-night stakeout leads to a confrontation at King’s house, where Roger and his team listen in on a plan to harm Geri. King finally confesses to the murders of both Ross and Verne, then turns on Roger, aiming to kill him. Geri springs into action, knocking King out with a vase, while Bates and Collins restrain Garrick and his henchmen. In the aftermath, Roger and Geri share a quiet, relieved moment, and Roger invites her to join his staff permanently, signaling a partnership built on truth, tenacity, and justice.
